How tight should the wishbone bolts / nuts be? The bolts are M12 x 70 marked with a tensile strength of 8.8.

I've got PU bushes and stainless steell crush tubes and am building an MK Indy.

Thanks

I've no idea what figure in torque units, but the crush tube shouldnt move. as tight as is necessary would be a good place to start, and then maybe a bit more. The bracket should not be squished into the actual bush though as it will eventually wear.

Are you using grease on the crush tube?

Having previously spoken to Polybush UK and decided not to use any form of lubrication, and then, having posted (and read) a few more threads during the past week, I decided to remove the tubes and re-fit them using a lithium based bearing grease (Castrol LM). This may, or may not, be ideal, but......... it's done.

"As tight as is necessary" is a bit vague, anything more specific would be appreciated. This has got to be an issue that we all face...

In the absence of anything else I have gone for the same torque setting as Haynes suggest for the Sierra diff to crosmember setting of around 90 NM, though having said that I feel that the wishbones feel a bit slack.

C'mon who's done what out there?

Ta!

Rorty has a torque calculator on his site, the torque setting has more to do with the fastener than the application

This must be one of the most asked questions !!!

At Stonleigh I askesd a Westfield engineer this question and he reckoned around 60lbs. This is very tight , but he reckoned that this is what they use on their builds. I tightened up mine to this torque and wait to see the results

It seems to be ok at present --awaiting road testing though !!!

Regards , Phil

MK7:

quote:

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How tight should the wishbone bolts / nuts be? The bolts are M12 x 70 marked with a tensile strength of 8.8.

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I tried the calculator on your web site and got the result 103 N-m.

How should the calculator be used in a nut and bolt application?

Russell

Just select the materials/bolt grade/size you're using, and hit the button!
BTW, I meant to add to my last post, the 8.8 marking on the bolt head is the nomenclature used for grading metric fasteners, and shouldn't be confused with Grade 8 imperial fasteners.
8.8 metric is closer to Grade 5. If you want high tensile metric fasteners, use 10.9 (they're actually a slightly higher tensile strength than Grade 8).

Thanks for clarifying that Rorty.

For the lay men (and women) among us it would be great to see the metric calculator graded in the units that are marked on the bolts.

Thanks again

Russell